The 47,XXY karyotype and unrelated malformative patterns: an unusual association

47,XXY chromosome complement is relatively frequent (1/750-1000 male newborns) but has so far not been reported in association with malformative syndromes. Three cases of 47,XXY karyotype associated with an unrelated malformative pattern, the Silver-Russell syndrome in two cases and Noonan syndrome in one case are reported. The possibility of a phenotypic alteration of patients with the XXY karyotype by these malformative syndromes is considered.